Mixed secondary alkyl amide synthetic lubricant compositions

ABSTRACT

Mixtures of amides of secondary alkyl amines for use in lubricant compositions.

United States Patent 1 McCoy et a1.

[ 1 July 15, 1975 MIXED SECONDARY ALKYL AMIDE SYNTHETIC LUBRICANT COMPOSITIONS [75] Inventors: Frederic C. McCoy, Beacon; Larry D. Grina, Wappingers Falls, both of [73] Assignee: Texaco Inc., New York, NY.

[22] Fi1ed: Nov. 5, 1973 [21] Appl. No.: 413,093

[52] US. Cl 252/515 A [51] Int. Cl. CIOm l/32; C10m 3/30 [58] Field of Search... 252/51.5 A

[56] References Cited UNITED STATES PATENTS 3,312,620 4/1967 Low et a1 252/515 A X OTHER PUBLICATIONS Smalheer et a1., Lubricant Additives, p. 8, Lezius-Hi1es Co., 1967.

Primary Examiner-De1bert E. Gantz Assistant ExaminerAndrew H. Metz Attorney, Agent, or Firm-T. H. Whaley; C. G. Ries; Robert A. Kulason [57] ABSTRACT Mixtures of amides of secondary alkyl amines for use in lubricant compositions.

24 Claims, No Drawings MIXED SECONDARY ALKYL AMIDEzSYNTHETIC LUBRICANT COMPOSITIONS BACKGROUND OF THE INVENTION:

Synthetically derived organic liquids have been used for many years as supplements to, or replacementsfor, petroleum hydrocarbons in the formulation of hydraulic fluids, gas turbine lubricants, greases and, toa lesser extent, crankcase lubricants The use of synthetic supplements or additives for these purposes, for example, synthetic aliphatic diesters, has been prompted by their possession of a number of desirable lubricant properties including generally their low volatility. suitably high viscosity and their abilityto permit operation of equipment over wider temperature ranges than would be possible with mineral oils alone. The use of nitrogencontaining synthetic lubricants, by way of illustration, tertiary alkyl primary aliphatic amines, tertiary butyl formamide and the like has also been projected. While satisfactory for many purposes the use of these various compositions has been limited heretofore by one factor or more frequently a combination of factors, such illustratively as excessive reactivity, too high a freezing point, too low a viscosity index or too great a cost for various purposes by reason of involved manufacturing procedures or relatively expensive source materials even though desired viscosities are otherwise attained.

Thus, the discovery of lubricant base compositions having substantial chemical stability and available from relatively inexpensive source materials by facile economic modes of manufacture, while evidencing inter alia, and simultaneously a desirable viscosity, viscosity index, pour point and freezing point would represent a significant advance in the relevant art.

SUMMARY OF THE INVENTION:

It is a primary object of this invention to provide an improved lubricant base incorporating a desirable interrelationship of viscosity, pour point and viscosity index and capable of preparation from inexpensive source materials.

Other objects and advantages of this invention will become evident from the following description.

Accordingly, it has now been discovered that monoand di(secondary alkyl) N- substituted amides, wherein each alkyl moiety attached to the nitrogen atoms contains from I to 25 carbon atoms, provide a synthetic lubricant composition possessed of an efficacious viscosity and viscosity index, low pour point and good thermal and oxidation stability and other desirable properties particularly adapted for use in lubricants.

DESCRIPTION OF THE PREFERRED EMBODIMENTS:

The lubricant base compounds of this invention are mixtures of amidcscharacterized by the general formula:

wherein R is selected from a hydrogen atom, a primary alkyl radical containing from 1 to 25 carbon atoms, and a secondary alkyl radical containing from 5, and preferably 7, to 25 carbon atoms; R is a secondary alkyl radical of from 5, and preferably 10, to 25 carbon atoms;

ll N-C-(CIM- whereinR and R havethe values recited for R and R respectively hereinabove; .r is a num'eral of from 0 to 12 inclusive, and more desirably from O to-8; al-' though the most preferred is that in which is an integer offrorn about 2 to 6. Theparticularmi'xtures of the foregoing amide contemplated according to'this invention are those wherein each such mixture' is further characterized by the presence substantially of a group of amides of the foregoing formulae wherein the secondary alkyl radicals present contain carbon chain lengths within the range substantially of 5 to 10 carbon atoms; 16 to 18 carbon atoms; 17m 20 carbonatoms; l9 to 22 carbon atoms; and 22 to 25 carbon atoms; and wherein amides containing each of said chain lengths are present in each of said mixtures.

Thus included within the scope of this invention are mixtures of amides composed of the foregoing fractions having the formula:

Ill

wherein R is a hydrogen atom or an alkyl radical of from I to 20 carbon atoms inclusive; and each of R and R" has the values recited above.

Also included within the lubricant base compositions of this invention are mixtures of diamides of the formula:

wherein each of R, R", R R and x has the values recited above.

The preferred compounds for use in the practice "herein described are those amides of Formula III, particularly, and in Formula IV, wherein R" (and R if present) are secondary alkyl moieties of the fraction containing 10 to 14 carbon atoms; and R (and R where present) are mixtures of the foregoing secondary Clo-C alkyl fraction or a lower primary alkyl radical, e.g., l to 7 carbon atoms. Particularly preferred of the diamides of Formula IV are the diamides wherein each of the amine components is derived from a secondary alkyl secondary amine and wherein the secondary alkyl moieties are from C to C and x is a numeral of from O to 8. These preferred compositions excel in their combination of desired lubricant properties, eg, lower melting points and other low temperature properties.

Illustrative of the amides of Formula III are the formamide of (C -C secondary alkyl) primary amines; the acetamide of (C -C Secondary alkyl) primary amines; and the acetamide of di(Cm-C secondary alkyl) amines.

The following compounds are illustrative of the diamides of Formula lV appearing hereinabove: di(C- nrC econdary alkyl) secondary diamide of sebacic acid, methyl (Cm-C Secondary alkyl) secondary diamide of oxalic acid; and di(CwC secondary alkyl) secondary diamide of succinic acid.

The amides of this invention are derived generally from the conventional reaction of secondary alkyl amine and an aliphatic monocarboxylic acid or dicarboxylic acid, its corresponding anhydride or acyl chloride, or in the event of formamide production. methyl formate.

The amine reactants are, as indicated, (secondary alkyl) primary amines or secondary amines in which one dary amines employed herein are not considered critical, certain percentages of the individual component paraffin hydrocarbons are preferred. These preferred distributions of various carbon chains within the fractions of secondary alkyl primary amines used in the practice of this invention, and from which the secondary alkyl secondary amines are also prepared, are illustrated in the following Table l and Table ll, together with other properties of these amines.

TABLE l Cur-C SECONDARY ALKYL PRIMARY AMlNES Composition [ti IA u i5 or both of the substituents on the nitrogen are secon- 5 w:.% G.C. Undis- Pis- Pisdary alkyl, preferably the latter. Analysis tlllcd tilled tilled Thus, in the case of a secondary amine one of the mmmffin 10 amine substitutes may be a primary alkyl. H O 1.0 The term (secondary alkyl) amine is intended to embrace those amines wherein the nitrogen atom is 10- com onent cated randomly and predominantly on other than the g 2-? 2-8 terminal carbon atom of at least one paraffin group and 51: 56:0 05 particularly the straight chain paraffin constituting the gm 3% 3-? alkyl substituent. I 1 Suitable amines are, by way of illustration, those prem pared according to the procedure described in U.S. Pat. No. 3,470,252 and involves briefly the nitration secondary amines 3.7 using, for example, nitrogen dioxide, nitric acid or dini- Tom] trogen tetroxide, in a liquid-vapor process, of paraffin 90+ 98+ 98+ hydrocarbon mixtures, including illustratively, n g f" Base Nov 293 312 267 decane, n-dodecane, n-tridecane, n-tetradecane, niffig wt. 7,4 pentadecane, n-octadecane, n-eicosane, n-pentacosane Avg. Mo|. W1. I87 220 and the like and preferably those containing from 10 to 8028 07984 14 carbon atoms. 1-720 mm 226-230 300-385 A ho h the amounts of araffin h drocarbon com- Ffccling Point h p Color. ASTM 2.5 1.0 0.5 ponent present in a particular fraction, for example, C o-C Cu-Cm, (rm-C 3, C1720, Cur-C Of the secon- Gas chromatography TABLE II C ,C SECONDARY ALKYL PRIMARY AMINES Composition, Wt. '7r. *G.C. Analysis C -C C rur- 22 nParaffin 4.0 1.4 8.4

2 (1.0) secondary alkyl amine component is 1.5 2.4 0.6 m L7 0.5 C l7.8 9.0 C 46.4 10.2 0.6 Cm l3.4 30.5 4.5 c 5.0 30.| 7.6 C), 5.9 9.5 32.8 C21 2.8 4.9 25.2 C 1.2 L1 10.4 0, 0.3 0.4 9.9 Total l 00.0 l00.0 l00.0

Amines, Wt. /'r 90+ 90+ 90+ Total Base No. 2l6 203 188 Basic nitrogen.% 5.0 50 44 Av. Mol. Wt. 239 256 289 Density 0.8324 0.8083" 0.8 l Freezing Point. "F 37 43 6| Color, ASTM 5.0 3.0 5.5

"At 20C "At I00F Gas chromatography Moderate variations in the percentages of the amine components, i.e. fi percent within a particular molec ular weight range, for example C, C do not affect the desirability of the preferred distribution of various chain lengths in mixtures of Table l and II for the purposes of this invention.

Nitration is effected so that the nitro group is randomly distributed along the paraffin chain providing, in turn, the (secondary alkyl) primary amine when converted thereto in a sequential hydrogenation step using a conventional hydrogenation catalyst. The primary amine is, when hydrogenation is completed, isolated and recovered from the reaction product mixture.

When a di(secondary alkyl) amine is desired the primary amine may simply be further reacted in situ, prior to recovery from the initial hydrogenation reaction product mixture, or as a separate step, at an elevated temperature, illustratively, 190C to 220C, in a hydrogen atomosphere of 50 pounds per square inch gauge (psig) to l000 psig over a reduced nickel/nickel oxide catalyst supported on kieselguhr, in which the ratio of reduced nickel to total nickel present is 0.6 to 1 respectively. Ammonia, as well as gaseous hydrogen, is most desirably removed from the reaction vessel as the reaction proceeds.

Similarly these secondary amines may be prepared by heating two moles of primary amine to about 200C in the presence of about 4.0 weight percent Raney nickel. This method is less preferred, however.

Other illustrative means for preparing the secondary amines for use herein include reacting the preferred secondary alkyl primary amines with aliphatic aldehydes (preferably formaldehyde) to prepare the corresponding Schiff bases. These can be readily hydrogenated to give secondary amines in which one of the substituents on the nitrogen is the secondary alkyl group of the original amines and the other is the alkyl group corresponding to the aldehyde used. When formaldehyde is used, the alkyl group is methyl. The product, as will be evident, is one in which the amine product contains a secondary alkyl and primary alkyl substituent. These mixed secondary amines are generally less preferred for use in the practice of the invention.

Where the amides are prepared from an aminealiphatic acid reaction, equimolar amounts of the secondary alkyl amine and an aliphatic acid are heated in the presence of an azeotroping solvent, for example, benzene, toluene, xylene, n-heptane or the like, until a mol of water is recovered. Suitable acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, pelargonic acid, and isostearic acid. Preferred reactants are propionic acid, acetic acid, and particularly formic acid. Thus appropriate are those saturated aliphatic carboxylic acids containing from 1 to 30 carbon atoms, but most desirably those with a melting point of 25C or less.

Alternatively, equimolar amounts of secondary amine and aliphatic acid anhydride may be heated to reflux for about one hour, at the end of which time one mole of aliphatic acid is distilled off. The remaining product is dissolved in an equal volume of inert organic solvent, for example, pentane, washed with mild alkaline solution, illustratively, a ten percent aqueous solution of NaHCO dried and the pentane or other solvent removed by stripping. This reaction is undertaken most desirably with the anhydrides of the lower saturated aliphatic carboxylic acids containing from two to four carbon atoms, e.g., acetic anhydride, propionic anhydride, and butyric anhydride.

As noted above, where formamides are being prepared from primary amines, a desirable procedure involves reacting a molar amount of secondary alkyl amine with 10 moles of methyl formate. The reaction is undertaken, illustratively, in a rocker bomb to which the reactants are charged and which is then heated to from about 1 10C to about [35C and shaken for about seven to twenty-four hours, after which the reaction product mixture is cooled and the contents distilled to remove excess methyl formate and methanol. The residue remaining is the desired amide product.

The diamides are conveniently prepared by conventional techniques wherein 1 mol of secondary amine is reacted with 0.5 mol of dicarboxylic acid chloride or dicarboxylic acid anhydride.

The amides so produced constitute satisfactory lubricants for a variety of purposes, for example, as crankcase lubricants. They may, desirably, as indicated above, provide the entire lubricant vehicle and will, in any event, constitute a substantial or major portion by volume of any lubricant composition of which they are part.

A very desirable and unexpectedly improved lubricant composition has also been found to be formed by a blend or mixture formed from at least 30 percent of one of the foregoing amides of this invention and a lubricant thickener, such as for example, a polybutene containing about 98 percent by weight of high molecular weight monoolefins and the remainder isoparaffins; or a polymethacrylate thickener.

Most desirably the molecular weight of these polybutenes is within the range of about 1900 to 2800.

The polymethacrylate thickeners are most desirably those methacrylate copolymer-containing compositions, incorporating, by way of further illustration, about 65 percent by weight of mineral oil and 35% by weight copolymer. The mixture has a viscosity at 210F (SUS) of 4400 to 4600. The methacrylate copolymer is a mixture in turn of polymeric methacrylates of nbutyl alcohol in a weight ratio of about 18 percent to about 25 percent, and preferably about 21 percent; of n-dodecyl alcohol in an amount of 50 percent to about 55 percent, and preferably about 53 percent; of noetadecyl alcohol in an amount of from about 20 percent, and preferably about 22 percent; and about 2 percent to about 8 percent, and preferably about 4 percent, of N, N-dimethyl B-amino ethyl alcohol.

Amide lubricants of this invention may also be fortified, optionally with conventional additives, if desired, such as antioxidants, e.g., phenothiazine; conventional detergents, anti-foaming agents including silicones, e.g., silicone (dimethyl silicone polymer) anti-foaming agent in a petroleum solvent, corrosion inhibitors or thickeners other than the methacrylate and poly (butenes) recited above and the like, in standard proportions. The low pour points of the amides of this invention obviate normally the necessity of including pour depressant additives which would otherwise be clearly essential.

The lubricant oils devised in accordance with this invention, with or without fortification with additives such as the foregoing may be incorporated into, for example, an SAE l0W4O motor oil, a gear oil, or an auto- Composition Percent by Volume A paraffinic mineral oil 40 Di(C ,C secondary alkyl) 38.5

acetamide Polymethacrylate Thickencr 9.5

(as characterized above) Balanced detergent and anticorrosive additive mary amines with methyl formate in a molar ratio of amine to methyl formate of 1:10 respectively in'a pressure vessel for'a period of 7 to 24 hours at a temperature of l 10C to I35C. After completion of the reaction, the reaction vesselwas cooled and the contents distilled to remove excess methyl formate and one molar equivalent of methanol. The residueremaining in the reaction vessel was the product, (C -C secondary alkyl) primary amide.

Ultra-violet analysis of the (C -C secondary alkyl) formamide recovered showed no unreacted amine present.

The viscosities, viscosity indices, and pour points of the foregoing amide of the invention and those of a commercial C substituted formamide were determined and the test results recorded in Table III.

TABLE III Viscosity.cs.. Viscosity Pour Lubricant Composition lOF 2l0F Index Point-F PRIMID Fl 2 (Formamide of C tert. alkyl primary amine) 220.8 7.76 -l80 m-C secondary alkyl) formamide 44.2 5.56 54 The foregoing blended formulation was found to have the following physical properties:

Viscosity at I0OF. SUS 443 Viscosity at 210F. SUS 84 Viscosity Index 200 Viscosity at 0F (Extrapolated) SUS 10,000 Pour Point. F 50 The paraffinic mineral oil employed in the foregoing formulation is one characterized by the following physical properties:

API gravity 31.5 to 33.5 Flash point (Cleveland Open cup method) 400F minimum Viscosity at IOOF SUS I23 I33 Viscosity at 2I0F SUS 4l.5 minimum Viscosity Index 95 ()F maximum .003 maximum Pour Point Ash. Wt. 71

EXAMPLE I This example illustrates the favorable physical properties of the (Cw-C secondary alkyl) formamides of the invention with respect to their use as synthetic lubricants.

The (C C secondary alkyl) primary formamides were prepared by reaction of the corresponding pri- It will be evident from the foregoing Table III that the (C -C secondary alkyl) formamide of this invention is superior to the commerically available formamide of C tert. alkyl primary amines both as to pour point and viscosity index.

EXAMPLE II This example illustrates the desirable physical properties resulting from the presence of a random secondary alkyl structure of the (secondary alkyl) amines used in the preparation of the amide lubricants of the invention.

In order to study the unexpected low pour points of the amides of secondary alkyl primary and secondary amine lubricants of the invention, in contrast with the amides prepared from other amines, the acetamides appearing in Table IV. including the acetamides of (C C secondary alkyl) primary and secondary amines, and the methyl C C secondary alkyl secondary amines were prepared by reacting the amines with a ten percent molar excess of acetic anhydride, removal by distillation of a mol of acetic acid, neutralization of excess acidity with NaHCO and drying and filtration of the residue. The acetamides chosen by way of contrast in Runs 2 and 3 of Table IV have about the same molecular weight as the acetamide coming within the practice of this invention and reported upon in Run l, of Table IV. The propionamide and the isobutyramide of Table IV were made using propionic anhydride and isobutyric anhydrides, respectively. The amine used in preparing the acetamide of Run 5 was made'by reacting CwC secondary alkyl primary amine with formaldehyde and subsequently hydrogenating to the secondary amine.

Vise. lndex Run No.

Viscosity. cs.

Composition I l 00F 2l0F Pour Point, F

1 Acetamide of m- 14 ondary alkyl) primary amines Acetamide of Primene 8l-R (C tertiary alkyl primary amines)* 3 Acetamide of n-Dodecylamine Solid melting point molecular weight. theoretical: 227; obsen ed: molecular weight. theoretic' 390; observed: molecular weight. theoretical: 240; observed:

it will be evident from the pour point and viscosity determinations of Run 1 of Table II for the acetamide of the secondary alkyl primary amines of the invention that this acetamide has materially different, and, from the aspect of its value as a lubricant, more desirable properties than those of the acetamides of the other amines recited in Runs 2 and 3 of this same Table lV, although the compounds have about the same molecular weights.

The acetamides of di(C C secondary alkyl) secondary amines (Run 4) and methyl (C -C secondary alkyl) secondary amines (Run 5) present an even more striking comparison in pour point and viscosity demonstrating the unique and unexpectedly superior properties relative to synthetic lubricant applications inherent in the presence of the random secondary alkyl structure and the replacement of a hydrogen on the amide nitrogen (for example,- Runs 2 and 3) with illustratively, a secondary alkyl group (Run 4) or a methyl group (Run '5) in the amides of the invention. The exceptionally high viscosity at'100F ofthe acetamide of a (C tertiary alkyl) primary amine in Run 2 suggests that the product might have formed a polymer but a molecular weight determination revealed that the amide had remained monomeric. At the same time the actual molecular weights of the acetamides of Runs 4- and 5 were sufficiently closeto the theoretical to indicate a monomeric structure and demonstrate,:in contrast with the viscosities and pour points secured in Run 2 and 3 for'ace'tainides of significantly lower molecular weights, the importance of the aforesaid random secondary alkyl relationship.

While 'not intending to belimited to any particular mechanism or theory of operation, it is believed that the superior pour point and viscosity shown by each of the acetamides of the invention results from a special intermolecular or intramolecular association between the acetamide molecules resulting from the presence of one or two secondary alkyl substituents on the nitrogen atoms of the amides. This is further illustrated by the low pour points observed on the amides of Runs 6 and 7.

EXAMPLE III This example illustrates the preparation and superior properties of the diamides for use in lubricant compositions.

a. One mol of each of the specific secondary amines indicated in Runs 1 to 3 of Table V which follows, i.e.,

di(CwC secondary alkyl) secondary amine (Run 1);-

methyl (C -C secondary alkyl) secondary amine (Runs 2 and 3), was reacted with 0.5 mol of the corresponding acid chloride recited in each of the foregoing Runs, i.e., sebacoylchloridelRuns l and,2.) .an d oxalyl chloride (Run 3), in astirred flasks to which thesecondary amine and 1 mol of triethylamine were 1 first charged and the acid chloride then added slowly with cooling at 25C to 35C. The reaction mixture was stirred for a period of six (6) hours, diluted with an equal volume of pentane and filtered. The pentane was stripped and the resulting diamide, that is the di(C- w-C Secondary alkyl) secondary diamide of sebacic acid (Run 1); methyl (C -C secondary alkyl) secondary diamide of sebacid acid (Run 2.); and the methyl (C 'C .secondary alkyl) secondary diamide of oxalic acid (Run 3), respectively, secured and tested as shown in Table V.

b. Two mols of the secondary amine, di,(C|0 C secondary alkyl) secondary amine, were charged with 1 gram of toluene sulfonic acidand 1 mol of succinic anhydride to a stirred flask with 200 milliliters of xylene. The mixture was heated to reflux until the theoretical water content was recovered. The reaction product mixture was diluted and cooled with 400 milliliters of pentane and washed with percent sodium hydroxide solution. The product, the diamide of di(C -C seconforegoing composition being sold under the tradename INDOPOL) was blended with di(C --C secondary alkyl) acetamide in the proportions by volume indicated in Table VI. As noted in this Table. the blends evidary alkyl) secondary amine and succinic anhydride, 5 denced high viscosity indices. a feature most desirable that is di(C C secondary alkyl) secondary diamide m lubricant oils and indeed higher viscosity indices of succinic acid. was secured by drying. filtration and than those of the components of the blends as evistripping of the pentane and xylene therefrom. and denced in Table VI. In addition, the blends manifested tested as shown in Run 4 of Table V. low pour points.

TABLE V Run Visc.. cs., Visc. Pour No. Composition 100"] 2IOF Index Point.F

l Diamide from m- H ondary amines and sebacoyl chloride 157.7 l6.ll 115 5() 2 Diamide from methyl mu ondary alkyl) secondary amines and sebacoyl chloride 299.8 22.8 102 2.5 3 Diamide from methyl (C C H secondary alkyl) secondary amines and oxalyl chloride 64.8 6.88 53 55 4 Diamide from K IU I-I ondary alkyl) secondary amines and succinic an hydride 73.6 l0.00 128 60 TABLE VI Composition Percent K lit H secondary alkyl acetamide (7: by volume) 80 85 l00 INDOPOL H I900 poly (butene) by volume) I5 I00 Test Results: Viscosity at lO0F (cs) 147.8 98.9 170.000 4.49 Viscosity at 2lOF (cs) l6.76 12.48 4,0l3 27.6 Viscosity index 131 I I22 70 Pour Point. "F 7() The combination of superior properties comprising viscosity, viscosity index and pour point manifested by the diamides is evident from the foregoing Table V.

EXAMPLE IV This example illustrates the unexpected advantages resulting from the formation of a blend of an amide of the present invention with a polybutene polymer.

Standard test methods were utilized in the determinations apperaing in the tables of the foregoing examples. Thus, viscosity index was measured in each instance according ASTM D 2270; viscosity cs at lO0F and 210F was determined using ASTM D 445; and pour point data was arrived at utilizing ASTM D 97. The foregoing test methods were also those employed in arriving at the values accorded in terms of viscosity, viscosity index and pour point elsewhere herein.

As an adjunct to use of the amides of (secondary alkyl) amines in accordance with the invention as lubricants alone. the combination of these amides with butene polymer or polymethacrylate thickener to secure an even further improvement in lubricant properties is of obvious value.

It will be evident that the terms and expressions which have been employed are used as terms of description and not limitation. There is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof and it is recogniqed that various modifications are possible within the scope of the invention claimed.

What is claimed is: l. A synthetic lubricant oil composition comprising a mixture of amides selected from the formulae:

wherein R is selected from a hydrogen atom and an alkyl radial containing from 1 to 20 carbon atoms; each of R and R is a radical selected from a hydrogen atom, a primary alkyl radical containing from about 1 to about 25 carbon atoms and a secondary alkyl radical containing from about 5 to about 25 carbon atoms; each of R" and R is a secondary alkyl radical of from about 5 to about 25 carbon atoms; and x is a numeral of from about to about 12; and said mixture is further selected from the group of amides of the foregoing formulae wherein the secondary alkyl radicals present contain carbon chain lengths within the range substantially of to carbon atoms; 10 to 14 carbon atoms, 14 to 15 carbon atoms, 16 to 18 carbon atoms, 17 to 20 carbon atoms; 19 to 22 carbon atoms; and 22 to 25 carbon atoms, said amides in said mixture having secondary alkyl substituents of each of said chain lengths present therein.

2. A lubricant oil composition comprising a mixture of amides as claimed in claim 1 wherein the amides in said mixture contain from 10 to 14 carbon atoms.

3. A lubricant oil composition according to claim 1 wherein said mixture constitutes at least thirty percent by volume thereof.

4. A lubricant oil composition according to claim 3 wherein said mixture of amides has the general formula:

5. A lubricant oil composition according to claim 3 wherein said mixture of amides is a diamide of the formula:

6. A lubricant oil composition according to claim 3 wherein said amide is present in an amount by volume of at least forty percent.

7. A lubricant oil composition according to claim 3 5 where said amide is present in a major amount by volume.

8. A lubricant oil composition according to claim 6 wherein said amide is the formamide of (C -C secondary alkyl) primary amines.

9. A lubricant oil composition according to claim 6 wherein said amide is the formamide of di(Cm-C secondary alkyl) secondary amines.

10. A lubricant oil composition according to claim 6 wherein said amide is the acetamide of (Cm-C secondary alkyl) primary amines.

11. A lubricant oil composition according to claim 6 wherein said amide is the acetamide of di(C,.,-C secondary alkyl) secondary amines.

12. A lubricant oil composition according to claim 6 wherein said amide is the acetamide of methyl (Cm-C secondary alkyl) amines.

13. A lubricant oil composition according to claim 6 wherein said amide is the propionamide of di(C10-C secondary alkyl) amines.

14. A lubricant oil composition according to claim 6 wherein said amide is the butyramide of di(C C secondary alkyl) amines.

15. A lubricant oil composition according to claim 6 wherein said diamide is di(C C secondary alkyl) secondary diamide of sebacic acid.

16. A lubricant oil composition according to claim 6 wherein said diamide is di(C ,C secondary alkyl) secondary diamide of sebacic acid.

17. A lubricant oil composition according to claim 6 wherein said diamide is methyl (C -C secondary alkyl) secondary diamide of oxalic acid.

18. A lubricant oil composition according to claim 6 wherein said diamide is di(C C secondary alkyl) secondary diamide of succinic acid.

19. A lubricant oil composition according to claim 3 wherein the remainder of said composition comprises a lubricant thickener selected from the group consisting of polybutene and polymethacrylate.

20. A lubricant oil composition according to claim 19 wherein said thickener is polybutene.

21. A lubricant oil composition according to claim 20 wherein said thickener is a polybutene having a molecular weight of from about 1900 to 2800.

22. A lubricant oil composition according to claim 19 wherein said thickener is a polymethacrylate.

23. A lubricant oil composition according to claim 19 wherein said thickener is a mixture of a methacrylate copolymer and a mineral oil.

24. A lubricant oil composition according to claim 23 wherein the ratio of methacrylate copolymer to mineral oil is about percent to about 65 percent. 

1. A SYNTHETIC LUBRICANT OIL COMPOSITION COMPRISING A MIXTURE OF AMIDES SELECTED FROM THE FORMULAE:
 2. A lubricant oil composition comprising a mixture of amides as claimed in claim 1 wherein the amides in said mixture contain from 10 to 14 carbon atoms.
 3. A lubricant oil composition according to claim 1 wherein said mixture constitutes at least thirty percent by volume thereof.
 4. A lubricant oil composition according to claim 3 wherein said mixture of amides has the general formula:
 5. A lubricant oil composition according to claim 3 wherein said mixture of amides is a diamide of the formula:
 6. A lubricant oil composition according to claim 3 wherein said amide is present in an amount by volume of at least forty percent.
 7. A lubricant oil composition according to claim 3 where said amide is present in a major amount by volume.
 8. A lubricant oil composition according to claim 6 wherein said amide is the formamide of (C10-C14 secondary alkyl) primary amines.
 9. A lubricant oil composition according to claim 6 wherein said amide is the formamide of di(C10-C14 secondary alkyl) secondary amines.
 10. A lubricant oil composition according to claim 6 wherein said amide is the acetamide of (C10-C14 secondary alkyl) primary amines.
 11. A lubricant oil composition according to claim 6 wherein said amide is the acetamide of di(C10-C14 secondary alkyl) secondary amines.
 12. A lubricant oil composition according to claim 6 wherein said amide is the acetamide of methyl (C10-C14 secondary alkyl) amines.
 13. A lubricant oil composition according to claim 6 wherein said amide is the propionamide of di(C10-C14 secondary alkyl) amines.
 14. A lubricant oil composition according to claim 6 wherein said amide is the butyramide of di(C10-C14 secondary alkyl) amines.
 15. A lubricant oil composition according to claim 6 wherein said diamide is di(C10-C14 secondary alkyl) secondary diamide of sebacic acid.
 16. A lubricant oil composition according to claim 6 wherein said diamide is di(C10-C14 secondary alkyl) secondary diamide of sebacic acid.
 17. A lubricant oil composition according to claim 6 wherein said diamide is methyl (C10-C14 secondary alkyl) secondary diamide of oxalic acid.
 18. A lubricant oil composition according to claim 6 wherein said diamide is di(C10-C14 secondary alkyl) secondary diamide of succinic acid.
 19. A lubricant oil composition according to claim 3 wherein the remainder of said composition comprises a lubricant thickener selected from the group consisting of polybutene and polymethacrylate.
 20. A lubricant oil composition according to claim 19 wherein said thickener is polybutene.
 21. A lubricant oil composition according to claim 20 wherein said thickener is a polybutene having a molecular weight of from about 1900 to
 2800. 22. A lubricant oil composition according to claim 19 wherein said thickener is a polymethacrylate.
 23. A lubricant oil composition according to claim 19 wherein said thickener is a mixture of a methacrylate copolymer and a mineral oil.
 24. A lubricant oil composition according to claim 23 wherein the ratio of methacrylate copolymer to mineral oil is about 35 percent to about 65 percent. 